This invention relates to a multilayer film deposition apparatus. Especially, this invention relates to an apparatus preferably used for manufacturing perpendicular-magnetic recording media.
Thin-film deposition on a substrate is widely practical for manufacturing various kinds of products, e.g. electronics devices such as LSI, display devices such as LCD, and recording media such as magnetic recording disks. In such film deposition, sputtering is often employed because a high-quality film can be deposited at a high rate. A desired multilayer film is sometimes deposited by the sputtering on purpose to satisfy function of a product. For example, in the magnetic-recording-disk manufacture, after depositing an underlying film on a substrate, a magnetic film as the magnetic recording layer is deposited thereon. Not a mono-layer but a multilayer of different magnetic materials is sometimes deposited as the recording layer.
Multilayer film deposition apparatuses depositing such multilayer films are divided into two types in respect to the number of the deposition chamber. In one type of apparatuses, a multilayer film is deposited in one deposition chamber. In this type, multiple targets are provided in the deposition chamber. A substrate is transferred to each position facing to each target in order. In the other type of apparatuses, deposition chambers as many as the layers to be laminated are provided so that each layer can be deposited in each deposition chamber respectively. A substrate is transferred to each deposition chamber in order, in which each layer is deposited.
The sputtering is very practical for depositing such multilayer films. In the sputtering, a substrate is placed facing to a target that composes a cathode. Appling DC or high-frequency (HF) voltage to the cathode, sputtering discharge is ignited. During the sputtering discharge, particles of the same material as the target are released therefrom. Those particles, which are hereinafter called xe2x80x9csputter-particlesxe2x80x9d, reach the substrate, thereby depositing a layer. In depositing a multilayer film, the sputtering is repeated using multiple targets. Those targets are often made of different materials for depositing a dissimilar-multilayer film.
In the dissimilar-multilayer film deposition by the sputtering, cross contamination of the targets must be prevented so that property deterioration of each layer can be avoided. While one of layers is deposited by sputter-particles from a target prepared for itself, other sputtered particles from another target for another layer might reach the substrate, resulting in that the layer being deposited is contaminated.
Interlayer contamination must be prevented as well. If a substrate is exposed to contaminating atmosphere after depositing a layer before depositing the next layer, such interlayer contamination as surface oxidation may take place. Especially, in manufacturing magnetic recording media such as perpendicular-magnetic-recording disks, magnetic layers as many as about twenty are sometimes laminated. Because the layers are very thin, interlayer contamination may easily affect them if it takes place. When such layers for a perpendicular-magnetic recording disk are deposited in different chambers, interlayer contamination tends to take place easily. This is because the substrate may be exposed to contaminating atmosphere while it is transferred from one chamber to another chamber.
Productivity upgrading and occupation-space downsizing are still greatly required to multilayer film deposition apparatuses. High productivity and small occupation space are required even to apparatuses depositing such a large number of layers. To secure property of multilayer films, control of deposition conditions is also important. Pressure, gas flow rate and other parameters must be controlled at required values.
Object of this invention is to present a practical multilayer film deposition apparatus that can satisfy the described requirement. According to this object, this invention presents a multilayer film deposition apparatus comprising; a substrate holder to hold at least one substrate, a vacuum chamber in which a multilayer film is deposited by sputtering onto the substrate held by the substrate holder, plural cathodes that comprise targets respectively and are provided in the vacuum chamber, at least one sputter power source for applying voltage to the cathodes to ignite sputter discharge, and a main rotation mechanism for rotating each cathode together. The targets are arranged at positions where the center axes of the targets are located on a circumference. The main rotation mechanism rotates the cathodes around the axis in common to the circumference. The substrate holder holds the substrate at a position within an area in view to the direction of the axis. The area is formed of two loci of points on the rotated targets. One of the loci is drawn by the point nearest to the axis, and the other locus is drawn by the point furthest from the axis.